Method of manufacturing replaceable labyrinth type seal assembly



July 3 1 62 T. N. KELLY METHOD OF MANUFACTURING REPLACEABLE LABYRINTHTYPE SEAL ASSEMBLY Original Filed April 13, 1959 FIG.4.

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INVENTOR. THOMAS N. KELLY BY A. M l W ATTORNEY United States area-r Free6 Claims. c1. 29-455 This invention relates generally to a method ofmanufacturing replaceable labyrinth type seal assemblies, andconstitutes a division of myapplication filed April 13, 1959, hearingSerial No. 805,954.

Labyrinth seals are referred to as cellular and pressure seals, and area form of seal or packing used to prevent leakage between relativelyrotating, or rotating and stationary, members. They are commonly knownfor their use as pressure seals in axial flow compressors, turbines, andother rotating shaft equipment to prevent back flow along the shaft ofthe compressor, turbine or the like.

In compressors, turbines and similar rotating shaft equipment alabyrinth type seal having a multiplicity of sharp edged orifices inclose but spaced cont-act to a relatively rotating part is highlydesirable. However, it will be appreciated that in high speed and highthermal conductive equipment of the type mentioned there is a problem ofthermal conductivity. High temperatures due to friction or other factorsare readily transmitted to conductive materials and can cause failure byburning.

Thus far labyrinth type seals have been formed as an integral part ofone of the relatively rotating members,

wherein the seal is required, to avoid rather than eliminate the heatconductive problem at the base of the seal structure. To minimize thecost of such seals, both because of the integral construction requiredand of the problems of machining a major component part of the sealreceiving equipment, the cellular formation has been required to berelatively simple. The normal form is a plurality of annular ribs of oneor another cross-sectional shape. In seals of this type there is someheat dissipation in the seal forming annular fins, and such heat, as isconducted to the base of the seal, is transmitted directly into the partfrom which the seal structure is formed. Accordingly, failure to theseal at its junction with the part from which formed, is minimized.

Heretofore, insofar as I am aware, no one has proposed or suggested theuse of a separate member having a multiplicity of separate and isolatedrecesses or orifices, for forming a labyrinth type seal, and asuccessful method of manufacture thereof.

This invention discloses a pressure seal including a honeycomb sectionwhich is suitably formed and secured to a retaining ring to provide aseparate rather than integral sealing member. As a separate unit theseal is more easily installed and more readily replaced. Further, itsmalfunction does not require the replacement of an expensive componentpart but only of the relatively inexpensive seal itself. The method ofmanufacture employed produces a highly successful seal for its intendedpurpose without concern for burn-out between the seal and its retainingring structure.

It is an object of this invention to disclose a cellular or labyrinthtype pressure seal which is usable between concentric surfaces ofrelatively rotating parts and the like, and which comprises areplaceable separate sealing assembly rather than an integral part of amajor component of the seal receiving equipment in which the seal isused.

It is another object of this invention to disclose a pressure sealcomprising a preformed retainer ring and a honeycomb liner for saidring, wherein the liner has a multiplicity of separate and isolatedrecesses ororifices provided with sharply defined multiple outer edgeshaving good sealing characteristics.

It is also an object of this invention to disclose a pressure sealformed from a thin-walled honeycomb structure for maximum effective heatdissipation.

Another object of this invention is to disclose a paricular effectivemethod of forming a honeycomb section to provide. a cellular seal ofannular shape.

Still another object of this invention is to disclose a method of makinga successful labyrinth seal separate from rather than integral with, anymajor component part of the seal receiving st-mcture. i

A further object of this invention is to disclose a method of securing alabyrinth-forming honeycomb section to a retainer ring with immunity toproblems of burn-out and failure therebetween.

These and other objects and advantages in the practice of this inventionwill be more apparent upon a reading of the following specification; inconjunction with the accompanying drawing, wherein:

FiGURE 1 is a fragmentary cross-sectional view through a stationaryhousing and a rotating member, with the disclosed seal of this inventioninterposed between concentric flanges thereof and aflixed to the flangeof said housing, and showing parts broken away and in section.

FIGURE 2 is a fragmentary cross-sectional view through a stationarymember and a rotating shaft, with the disclosed seal of this inventioninterposed between concentric portions thereof and affixed to therotating shaft, and showing parts broken away and in section.

FIGURE 3 is an enlarged cross-sectional view through the disclosedpressure seal.

FIGURE 4 is a fragmentary elevational view of the seal structure shownin FIGURE 3.

FIGURE 5 is an enlarged edge view of the pressure seal disclosed by thisinvention, disposed separate from any equipment in which it might beused.

' FIGURE 6 is a further enlarged fragmentary elevational view of theseal structure to show the joint between abutting ends of the honeycombmember.

Referring to the drawings in further detail:

In FIGURE 1 there is shown a stationary housing 1 having a rotatablemember 12 disposed next adjacent thereto. The housing member 10 includesan annular flange or collar 14, and the rotatable member 12 includes aperipheral flange 16 arranged within and concentric with said annularflange 14. Between these closely disposed but spaced flanges 14 and 116is disposed the seal 20. v

In FIGURE 2 the sea1 20 is shown mounted on'a rotatable shaft 22 anddisposed in sealing relation to a stationary member 24 through which therotatable shaft extends.

The two illustrated embodiments, just mentioned, disclose the seal 20having an inner peripheral sealing surface or an external peripheralsealing face. It is also foreseeable that the sealing member 20 could beformed to have its sealing face radially disposed.

The seal 20 comprises a retaining ring 26 and a honeycomb member 28. V

The retainer ring 26 is formed from strip material and is channel-shapedin cross-section. Preferably the channel formation 30 of the ring opensinwardly and includes a pair of spaced parallel annular side walls 32and 34' between which the honeycomb member 28 is received.

The honeycomb member 28 is preformed and initially is astraight length.In the assembly illustrated, the initially straight preformed honeycombmember 28 has been curved lengthwise in the arc of a circle and isformed of V Patented Jul 31, 1962p separate thin or light gauge narrowcorrugated strips 36 disposed at substantially right angles to the baseof the channel formation 30 and arranged in parallel rows. Alternateapices of the corrugations of one strip engage and are secured toalternate apices of the corrugations of the next adjacent strip, as at38. This forms a multiplicity of separate and individual diamond-shapedcells or orifices 40 having flush sharply defined outer edges which aredisposed outwardly beyond the edges of the side walls 32 and 34 of thechannel formation and have good sealing characteristics.

The honeycomb member 28 is preferably formed so that it will fit snuglybetween the side Walls 32 and 34 of the channel formation 30 of theretainer ring, and alternate apices of the corrugations of the strips 36at opposite sides of said honeycomb member 28 may engage and may berigidly secured to the side walls 32 and 34 to form additional separateoutwardly opening triangular-shaped cells 41 that are approximatelyone-half the size of the diamond-shaped cells 40. Preferably the lengthof the preformed honeycomb member 28 is such relative to the insidediameter of the retainer ring 26 that the ends of said honeycomb memberwill firmly abut each other in end to end relation after said member 28is inserted within the ring 26. Thus no separate fixtures are requiredto hold said ends together when the member 28 is inserted into the ring26.

Referring to FIGURE 6, it will be noted that the abutting opposite endsof the honeycomb member 28 are preferably cut at complementary anglesextending diagonally across said member from one side edge to the otherthereof to form a continuous diagonal line of contact therebetween, asat 42. This arrangement provides a much more dependable connectionbetween the ends of the honeycomb member than would be had if the endswere cut straight across at right angles to the longitudinal median lineof said member. Further, the honeycomb pattern is not disrupted at theabutting ends of the member 28. In fact, the honeycomb pattern orformation is uniform throughout the circumference of the annulus formedby the member 28.

The seal is preferably assembled in the following manner:

The retainer ring 26 is preformed to the desired size and shapementioned.

The initially straight elongated honeycomb member 28 is curvedlengthwise in the arc of a circle by a rolling operation to the annularshape it is to assume in the retainer ring 26 of the seal assembly.Then, before being inserted within the retainer ring 26, the outersurface of said honeycomb member 28 is coated with a lacquer binder thatin turn is subsequently provided with a coating of brazing compound inpowder form. In fact, the curved honeycomb member 28 may be rolled inthe brazing compound after the outer surface thereof has been coatedwith the lacquer binder so that the compound is picked up only by thelacquer coated outer surface thereof. Opposite ends of said curvedmember are also coated with lacquer and brazing compound, and ifdesired, alternate apices of the corrugations of the strips 36 atopposite sides of the curved member may likewise be coated with lacquerand brazing compound.

The curved coated honeycomb member 28 is then placed within the annularretainer ring 26, with the coated surface of said member against thebase of the channel formation of said ring, and with opposite ends ofsaid member in abutting end to end relation. The honeycomb member 28 isthen tack or spot welded at circumferentially spaced points thereof tothe retainer ring 26 for attachment thereto, and the ends of saidhoneycomb member 28 are also tack or spot welded together for attachmentto each other.

Subsequently, the entire seal assembly is placed in a suitable furnacewherein the temperature is raised sufficiently to reach the fusingtemperature of the brazing compound. This causes the coated surfaceportions of the honeycomb member 28 to be permanently bonded to theretainer ring, and causes the ends of said member 28 to be permanentlybonded to each other.

The temperature required for the operation described varies with thetype of brazing compound used. A brazing composition of chrome, nickeland manganese has been found to require about 2100 degrees centigrade.

The resulting seal structure 20 is one which includes a multiplicity ofsmall, separate, deep substantially diamond-shaped recesses or orificesprovided with sharply defined multiple outer edges having good sealingcharacteristics and of thin dividing Wall or partition construction forbest heat dissipation.

The proposed seal is usable in axial flow turbines or compressors toprevent back flow along or any flow longitudinally of the turbine orcompressor shaft. The retainer ring is preferably press-fitted to areceiving member within a suitable receiving recess; but is in allinstances intended to be removable and replaceable. The outer exposedhoneycomb surface of the member 28 is to be in closely spaced butnon-contacting relation with the other relatively movable part of theseal receiving structure.

The seal disclosed may be used as an interstage sealing means whereseveral are used, and are disposed between stators of an axial flowcompressor or turbine wherein fluids are employed.

The seal is best used where pressure differentials are to be maintained.Such seal is not a contact seal, and relies upon the multiplicity oforifices having sharply defined outer edges to obtain the desiredsealing effect.

For high temperature environments the retainer ring 26 and honeycombmember 28 would both be formed from stainless steel or like compositionand would be brazed together as described. However, for low temperatureconditions the retainer and honeycomb member could be made of a fibrousor plastic material and could be secured together by other suitablebonding or adhesive substances.

What I claim as my invention is:

1. The method of manufacturing a replaceable labyrinth type sealassembly; comprising the steps of making a ring of channel-shaped crosssection and of predetermined diameter having the channel thereof openingradially, making a substantially annular honeycomb member ofpredetermined length having free ends and having a radial thicknessgreater than the depth of said channel with the cells thereof extendingradially, assembling the substantially annular member and ring byplacing said ring and member concentrically one within the other andthen radially flexing said member toward and within said channel so thatthe base of said channel will be in surface-to-surface engagement withthe adjacent radially facing surface of said substantially annularmember and said substantially annular member will project radially fromsaid channel beyond the edges of the side walls thereof and so that thefree ends of said substantially annular member will be in end to endabutting relation with each other, securing said radially facing surfaceof said substantially annular member to the base of said channel, andsecuring the abutting ends of said substantially annular member to eachother.

2. The method of manufacturing a replaceable labyrinth type sealassembly; comprising the steps of making a ring of channel-shaped crosssection and of predetermined diameter having the channel thereof openingradially, making an elongated substantially straight honeycomb member ofpredetermined length having free ends and composed of corrugatedseparately formed strips arranged in substantially parallel rows withthe alternate apices of the corrugations of adjacent strips connectedtogether and forming a multiplicity of separate cells and having athickness, measured between the opposite surfaces of said member throughwhich the cells extend, greater than the depth of said channel, curvingsaid straight elongated honeycomb member lengthwise in the arc of acircle so that the cells thereof extend radially and so that theopposite free ends thereof are positioned adjacent each other to therebyprovide a substantially annular member, assembling the substantiallyannular member and ring by placing said ring and member concentricallyone within the other and then radially flexing said member toward andwithin said channel so that the base of said channel will be insurface-to-surface engagement with the adjacent radially facing surfaceof said member and said member will project radially from said channelbeyond the edges of the side walls thereof with said strips disposedsubstantially at right angles to the base of the channel and so that thefree ends of said member will be in end to end abut-ting relation witheach other, permanently securing said radially facing surface of saidsubstantially annular member to the base of said channel, andpermanently securing the abutting free ends of said substantiallyannular member to each other.

3. The method defined in claim 1 including the steps, after assembly ofthe substantially annular member and ring and before, permanentlysecuring the radially facing surface of said member to the base of saidchannel and permanently securing the abutting free ends of said memberto each other, of tack welding said substantially annular member atcircumferentially spaced points thereof to said ring for attachmentthereto, and tack welding together the abutting free ends of saidsubstantially annular member for attachment to each other.

4. The method defined in claim 1, wherein the channel of said ring opensradially inwardly.

5. The method defined in claim 1, wherein the channel of said ring opensradially outwardly.

6. The method defined in claim 1, wherein the abutting -ends of thesubstantially annular member are cut at complementary angles extendingdiagonally across said member from one side thereof to the other.

References Cited in the file of this patent UNITED STATES PATENTS

